It is known in the field of amphibious vehicle operation and control to be provided with marine jet drive or impeller pods for vehicle assemblies such as in U.S. patent applications 2004/0014371, 2006/0172627 and 2007/0145751 also as in U.S. Pat. Nos. 7,241,193, 7,214,112, 6,971,931, 6,808,430, 6,364,725, 6,045,418, and 5,421,753 which includes an inlet a pumping means and an outlet nozzle.
Electric Jet drives such as described within pending application publication number 2007/0145751 substitute an external drive motor with an integrated electric drive that lacks control as to dynamic nozzle sizing or geometry with the associated electrical input power. These drives lack control of efficiency over the operational envelop of various vehicle speeds; thus, limiting the usefulness and utility of jet drives within various types of marine vessels including amphibious craft.
Electric Jet drives such as described within U.S. Pat. Nos. 7,241,193, 5,658,306, 5,679,035 and 5,683,276 disclose control systems for control of inlet duct, vane control of the impeller pitch and outlet nozzle sizing that relate to shaft rpm, head pressure and pump affinity constants to compute system flow for a derived power requirement of the pump that does not take into account the real applied power and that lacks control as to dynamic nozzle sizing or geometry with the associated real input power; thus, limiting the usefulness and utility of monitoring true efficiency of jet drives within various types of marine vessels including amphibious craft due to the control system estimation errors, and the associated complexity and reliability problems of variable-pitch impeller blades.
Current amphibious vehicle control systems incorporate the use of ground based wheel drive systems and separate jet drive or pod drive systems for operating within the water wherein said drive systems consist of a non-rotatable drive shaft support structures and bearings with an impeller for rotation attached to a drive shaft coupled to a motor used to convert the rotational energy of the motor into fluid flow energy which introduces added weight due to the separate components of the marine drive and ground drive system; thus, increasing the weight and number of parts and limiting its utility.
A major disadvantage with the use of jet propulsion units is the necessity for a complicated drive train between the engine of the vehicle and the jet propulsion unit. An amphibious vehicle that employs a jet propulsion unit typically would include a gearbox coupled to the engine, a drive shaft coupled to the gearbox at one end and at the other end to the jet propulsion unit. The connections at each end of the drive shaft are of the flexible coupling type and the overall arrangement is generally cumbersome to install and maintain, as well as being expensive and bulky. The maintenance of the drive train requires the sourcing of replacement parts which increases parts inventory cost and complicates maintenance procedures.
A further disadvantage is that these jet propulsion arrangements encroach significantly further into the interior of a vehicle, when compared to similar horsepower in wheel or electric drive arrangements.
Various amphibious and marine jet drive and pod drive system configurations, and methods are referenced herein, and the entire teachings of which and their references sited therein are expressly incorporated by reference herein.
Such amphibious and marine jet drive control systems as previously described possess significant added weight that detract from their overall utility or lack efficiency over the entire operational envelop, as a result of said system configurations and/or lack of control methods; thus, affecting the performance and implementation capabilities of the referenced related art amphibious, marine and ground drive systems. Consequently, there is a need for improved amphibious, marine and ground drive and motion control system configurations that overcome the aforementioned and other disadvantages. Additional disadvantages of other amphibious and marine drive control systems include the lack of information related to applied torque values and the exit nozzle dynamics related to the applied torque values.